Document reader

ABSTRACT

An optical character reader for conversion of information to a machine readable code from a strip of alpha-numeric characters on the face of a document. It includes an elongated document slot along which the document may be hand guided through a predetermined path. Optical viewing means is provided across a scan line intersecting the path of the alpha-numeric characters. A character scanning assembly electronically generates images of each character. Recognition processing means encodes these images into a machine readable code. All of the physical, optical and electronic components are contained within a compact single enclosure.

BACKGROUND OF THE INVENTION

This invention relates to a document guide and recognition apparatus formachine reading of alpha-numeric characters that appear on the face of adocument. It constitutes a manually fed slot reader, where the documentis moved longitudinally by the user through a defined path on theequipment in order that its contents might be optically scanned andencoded into a machine readable code. The apparatus constitutes aself-contained remote peripheral which can be coupled to a hostprocessor.

Optical scanning of printed indicia in the form of alpha-numericcharacters has previously been accomplished by use of stationary scannerin automated equipment for feeding documents past the scanners, and byuse of hand-held portable wands for loose documents. Both types ofdevices are relatively expensive and typically require auxiliarysupporting equipment in addition to the scanner itself. Automatedfeeding of documents is justifiable only where large volumes ofidentical documents must be processed in a production batch. Whilehand-held wands are designed for intermittent use in applications suchas retail sales facilities, resulting scan quality available by freemovement of a wand across a document is variable. The path of movementof the wand must be carefully monitored by the user in order to assureaccurate scanning of the indicia.

The present disclosure has arisen from an attempt to produce aself-enclosed scanner requiring no external support other than a powersource and operative coupling to a host processor. It uses a guidingslot to assure proper relative positioning of the document and scanline. By applying optical character recognition techniques to thescanning process, it adapts to a rate of document speed which can bepractically imparted to a document by hand-feeding along the length ofthe slot. In eliminates the need for manual adjustment or carefuldocument positioning. The device is capable of being manufactured at arelatively low cost in order to permit multiple installations of thedevice in a facility such as a bank lobby or retail sales outlet.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the apparatus, illustrating its use;

FIG. 2 is a fragmentary plan view of the apparatus;

FIG. 3 is a sectional view taken along line 3--3 in FIG. 2;

FIG. 4 is a sectional view taken along line 4--4 in FIG. 2;

FIG. 5 is an exploded view of the document slot and character scanningassembly;

FIG. 6 is an enlarged plan view of the character scanning assembly;

FIG. 7 is a corresponding elevation view;

FIG. 8 is an enlarged sectional view taken along line 8--8 in FIG. 7;

FIG. 9 is a sectional view taken along line 9--9 in FIG. 8;

FIG. 10 is a sectional view taken along line 10--10 in FIG. 8;

FIG. 11 is a schematic flow diagram of the electronic components.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present disclosure relates to a compact, manually fed opticalcharacterrecognition device in which documents are moved along a slotfor reading purposes. It is designed for reading a longitudinal strip ofvisual indicia 11 containing discrete alpha-numeric characters locatedalong the face 12 of a document 10. The document 10 illustrated in FIG.1 is a conventional check blank used for commercial banking purposes andhaving aprinted line of machine readable information that typicallyidentifies the bank, the user's account, and the amount of the check.

The document 10 has a constant thickness and can be made from a sheet ofpaper, paperboard, plastic or other suitable sheet material. Its face 12is bounded along one side by a planar longitudinal reference edge 13,which in this illustration constitutes the bottom edge of therectangular check blank. Document 10 has a predetermined width dimensionin a direction perpendicular to the reference edge 13. This widthdimension would be measured across the end edges 14 which extend betweenthe reference edge 13 and the remaining longitudinal edge 15 presentedalong the top of the check blank.

A strip of visual indicia 11 is located on the face 12 withintransversely spaced boundaries that are parallel to one another and arealso parallel to the lower reference edge 13 of document 10. In thisillustration, theseboundaries are coincident with the upper and loweredges of the alpha-numeric characters imprinted on the check blank.

As a general definition of the document geometry pertinent to thisdisclosure, the strip of visual indicia will have a transverse widthperpendicular to the document reference edge and will be arrangedparallelto said edge.

The present apparatus is provided within an enclosure generallydesignated at 16. The enclosure 16 has outer surfaces including an upperlongitudinalwall surface 17, a front wall surface 18, a rear wallsurface 20 and oppositely facing end wall surface 21. The enslosure 16as illustrated is rectangular in shape, and contains all the interiorcomponents of the apparatus in the completed assembly (FIGS. 1 through4).

The upper wall surface 17 and end wall surfaces 21 are interrupted by alongitudinal document slot 22. Slot 22 intersects the walls on whichthesesurfaces are formed and which extends the full length of enclosure16. Slot22 is a document guiding apparatus by which individual documents10 can be fed longitudinally the length of the enclosure 16 to permitmachine reading of the strip of visual indicia 11.

Located within enclosure 16 is a rigid frame generally shown at 33. Theframe 33 includes the stationary support elements for the variouscomponents of the apparatus. It includes upwardly protruding front andback longitudinal walls 23, 24 which are located in close opposedpositions. The walls 23, 24 have respective opposed inner surfaces 25,26 spaced apart transversely by a distance adequate to receive thethickness of a document 10 between them. They include coplanarlongitudinal upper edges 28, 30 and coplanar outer ends 31, 32,respectively. A base 27 extending between the inner surface 25, 26 ofthe two walls 23, 24 completes the boundaries of document slot 22. Base27 is positioned at a location spaced inwardly from the longitudinalupper edges 28, 30 of walls23, 24 a distance less than the height acrossthe document 10. The upper edges 28, 30 are located in close proximityto the upper longitudinal wallsurface 17 of enclosure 16. The slot depthis such that a document 10 can be manually moved within it in alongitudinal direction with respect to the rigid frame 33 and enclosure16. Document 10 is hand-held and guided along slot 22 by slidingengagement of base 27 by the document reference edge 13. This generaloperation is illustrated in the view shown in FIG. 1.

To facilitate entry of document 10 within document slot 22 from eitherend of enclosure 16, the outer ends of slot 22 are formed by inwardlyconverging surfaces 34, 35 formed at the respective longitudinal ends ofthe front and back walls 23, 24. The slot access openings presented bytheexterior wall surfaces 17 and 21 of enclosure 16 are correspondinglytapered in shape (FIG. 1). However, the operational section of slot 22intermediate its ends is formed with the inner surface 25, 26 of thefrontand back walls 23, 24 parallel to one another and spaced apart adistance slightly greater than the thickness of the document 10 designedto be fed between them.

The general assembly of the apparatus essentially comprises characterscanning means 36 mounted to the frame 33 and located within enclosure16 for electronically generating images of each alpha-numeric character.As will be described below, the character scanning means 36 is mountedon a separable support frame 37 that is detachably fixed to and formspart of rigid frame 33. The electronic components of the characterscanning means 36 are located on a printed circuit board 58 fixedalongside front wall 23(FIG. 3).

The apparatus is completed by electronic recognition processing meanslocated on the rigid frame 33 and also positioned within an enclosure16. The recognition processing means 38 is operatively connected to thecharacter scanning means 36 for analyzing the electronic imagesgenerated thereby and for encoding the images into a machine readablecode. It provides the final coded information at output terminals 40adapted to be wired to the Host Processor (not shown).

The recognition processing means is located on a printed circuit board41 rigidly secured to end support brackets 42, which in turn also mountthe slot stucture presented by walls 23, 24 and base 27. The electroniccomponents of the character scanning means 36 on circuit board 58 areconnected to components on the board 41 through ribbon conductors 60, 61arranged between the two upright boards. While the precise arrangementof the electronic components is not critical to an understanding of thisinvention, it is to be noted that all electronic components of thereader assembly are fully contained within the compact enclosure 16.

As an example of the practical application of this equipment, theillustrated apparatus might read a printed strip of visual indicia 11 onthe face 12 of a check blank and be utilized by bank tellers to verifythestatus of a customer's account by access to information stored in acentralcomputer memory. It might be similarly used by personnel in salesestablishments to verify the status of a checking account balance beforeaccepting or cashing the check written on the face 12 of the document10.

The details of the character scanning means 36 are best illustrated inFIGS. 5 through 10. The character scanning means 36 is mounted to theupright wall 43 and protruding shelf 44 of the separable support 37 as asubassembly which permits peralignment of the physical components of thescanning means prior to assembly on the remaining elements of the rigidframe 33. This also permits these components to be pre-aligned andreadilyreplaced as a unit for servicing purposes.

The support frame 37 includes a stationary wall surface area 45 (FIG.10) which is adapted to be slidably engaged by the document face 12. Thesection of upright wall 43 about area 45 serves as a document viewingassembly for reflecting light from the strip of visual indicia 11 ondocument 10. The details of this assembly are shown in FIGS. 8-10.

The front wall 23 along the open slot 22 has a complementary opening at46 to receive the wall surface area 45 of the frame 37 in a position atwhichthe surface area 45 is substantially coplanar to the inner surface25. To assure sliding engagement of the document face 12, it ispreferable that the area 45 be slightly radiused and protrude veryslightly beyond surface25 and extend within the confines of slot 22.

The opening 46 is located elevationally between the slot base 27 and thelongitudinal edges 28, 30 of the walls 23, 24. The distance between base27 and the mounted wall surface area 45 corresponds to the transverseseparation between the lower reference edge 13 of document 10 and thestrip of visual indicia 11. Thus, the moving strip of visual indicia 11will overlap the stationary area 45 as the document 10 traverses thelength of slot 22.

Light means is provided on the frame 37 for directing light onto theface 12 of a document 10 across the moving path of the strip of visualindicia 11. This light means is illustrated as four incandescent lamps47 mounted to the back of printed circuit board 58 and recessed withinthe upright wall 43 immediately outward from the wall surface area 45(FIG. 8). The light means also includes upright light guide slots 48which converge toward one another from the lamps 47 and openly intersectthe critical wall surface area 45.

Light sensing means 50 is mounted to shelf 44 of frame 37 for producinganalog signals at individual terminals proportional to the level oflight intensity directed to them. Means 50 in general comprises an arrayor matrix of light-responsive sensors for detecting the geometricrelationship to light values directed upon it. The unit illustrated is aconventional self-scanning linear photodiode Array which consists of asingle vertical row of silicon photodiodes. The individual outputterminals are shown as a bundle of conductors 51 leading to a receptacle52 at one end of wall 23 (FIG. 3), which in turn is wired to the propercomponents on the printed circuit board 41.

Optical viewing means is used between the light means and array 50 todirect reflected light from the face of document 10 to the array ofphotodiodes. The optical viewing means includes a narrow verticalviewing slot 53 that centrally intersects the two light guide slots 48at a plane slightly recessed from the wall surface area 45 (FIG. 8). Thewidth of theknife edge slot 53 is sufficiently narrow to have anaperture function in assuring viewing depth of field through it acrossthe permissible planar locations in which the face 12 of a document 10might be viewed within document slot 22. The narrow field viewablethrough the viewing slot 53 constitutes a scan line which is physicallypositioned with respect to document slot 22 so as to traverse the stripof visual indicia 11. The side edges of slot 53 formed through theupright wall 43 of subframe 37 converge outwardly ot permit maximumreflectance of light through the thickness of the upright wall 43. Thelight path, which is initially perpendicular to the wall surface area45, is turned 90° by the reflective surface of a mirror 54 mounted at anangle of 45° acrossshelf 44, and is beamed to focusing lenses 55, 56arranged along shelf 44 to properly direct the reflected light patternsfrom slot 53 onto the photodiodes of the Array 50. The lenses 55,56 andArray 50 are aligned parallel to the wall surface area 45.

Since the separable frame 37 contains the surface area 45 which thefield viewable through slot 53 must engage, the entire optical path fromdocument 10 to Array 50 can be prealigned on frame 37 independently oftheremaining components of the reader. This is much less cumbersome thanthe alternative of aligning the components on the total assembly andeliminates alignment of individual elements when servicing theequipment. Frame 37 is fixed as part of rigid frame 33 by releasablescrews 39 (FIG. 3).

Referring now to FIGS. 8, 9 and 10, the wall surface area 45 includesprovision for dispersal of environmental dust and solid particles thatmight otherwise collect about the area of the viewing slot 53 asdocuments10 are fed past it, particularly when the documents are madefrom paper or paperboard. To minimize the difficulties that areencountered due to dust,upright ventilation ducts 57 are formed withinthe upright wall 43 and surround the lamps 47. They openly intersect thelight guide slots 48. As discussed previously, lamps 47 are preferablyof the incandescent type, but might be any suitable heat emitting lightsource.

The ventilation ducts 57 provide convection cooling of the lamps 47 orother light means and dispersion of environmental dust in the vicinityof the viewing slot 53. Each duct 57 extends through the height of theupright wall 43 within the subframe 37 (FIG. 9) and has opencommunicationin frame 33 beyond the boundaries of the upright wall 43 atpositions aboveand below the width of slot 53. The lower end of eachduct 57 is open and unobstructed in the completed assembly. Ventilationof the upper end is assured through open communication along mating ductextensions 59 in wall23 (FIGS. 3,5).

As can be seen in FIG. 9, ducts 57 are preferably cylindrical aperturesformed parallel to one another and extending through the full height ofwall 43. Ducts 57 are in open communication with the complete height ofeach light guide slot 48. Upright movement of air within ducts 57 willtend to also draw air (and small dust or solid particles) from the edgesof the viewing slot 53. The moving currents of air will tend to dispersethis dust outside the viewing slot area, where it can come to rest onhorizontal surfaces within the enclosure 16 not critical to the opticalpath of the character scanning means.

FIG. 11 schematically illustrates the electronic components of thecharacter scanning means 36 and the recognition processing means 38,whichare generally outlined within dashed line boundaries.

The character scanning means 36 includes Array 50, which is illustratedby the RL 256G Array made by Reticon Corporation of Sunnyvale, Calif.This isa 256 element photodiode array of photodiodes as generallydescribed above.It is connected to an Array Drive 60, which provides allthe necessary signals to interface to and provide control of Array 50 asspecified by its manufacturer. The Array Drive 60 also generates all therequired signals to control the Quantizer 61 and the TransitionProcessor and Counter 62.

The Quantizer 61 basically functions as a comparator. The analog videosignal directed to it from Array 50 is compared within its circuitry toa reference voltage source. This reference voltage value was derived asa preselected percentage of the output from a peak white sample and holdcircuit within the Quantizer. A peak white follower circuit of theQuantizer tracks the maximum amplitude of the video signal coming fromArray 50. The output of the Quantizer comprises digitized videoinformation corresponding to the light values received on the individualphotodiodes in Array 50.

The Transition Processor and Counter 62 is a digital video processorwhich takes the digitized video information from Quantizer 50 in theform of a serial bit stream and analyzes it, one bit at a time, lookingfor valid transitions. A valid white to black transition for this readerwas definedas a sequence of at least two consecutive white bits ofinformation followed by at least two consecutive black bits. Similarly,a valid black to white transition is the reverse of this sequence. Thecircuit also counts the number of white or black bits received betweenvalid transitions. The white and balck count information is then passedon to the Direct Memory Access circuit 63.

The Direct Memory Access circuit receives count information fromTransitionProcessor and Counter 62. This count information is thendeposited into Picture Buffer 64. The Direct Memory Access scheme usedin this reader is a pseudo cycle stealing type technique, where allaccesses are done duringPhase I. Therefore no central processor time islost doing memory accesses.

The Picture Buffer 64 contains 16 bytes of Random Access Memory, whichare organized into two columns, 8 bytes each. It also has separateData-In andData-Out ports. The picture buffer is therefore a Read Onlyport for the recognition processor 65 and a Write Only port for theDirect Memory Access circuit 63. The Picture Buffer 64 appears to beonly one column long to both the recognition processor 65 and the DirectMemory Access circuit 63, because address bit 3 is not used by eithercircuit, thus utilizing a memory mapping technique. However, the logicstate of address bit 3 is changed once every scan of the Array 50, whicheffectively causesthe memory remapping function.

The recognition processor 65 is a Motorola MC6802 n-channel 40 pinIntegrated Circuit. It is manufactured by Motorola Corporation ofPhoenix,Ariz. It executes 72 variable length instructions and is alsocapable of directly addressing 65K bytes of memory. The 6802Microprocessor contains 128 bytes of internal Random Access Memorystarting at address 0000 and going to 007F (hexadecimal). It is properlyprogrammed to carry out the logical functions necessary for operation ofthe reader as described above.

The memory address space of the microprocessor 65 has been allocated toRead Only Memory, Input/Output, Picture Buffer, and Debug equipmentneeds.

There are no specific Input/Output instructions for the 6802Microprocessor. Therefore, Input/Output is done by using the "MemoryMapped" technique. This means that outputs from this system are the sameas a memory write, and inputs are the same as a memory read.

The recognition processor memory (ROM) 68 within is basically split intotwo halves. The top half is reserved for Debug equipment usage and thebottom half is allocated to the recognition part of this system.

Since address bits 13 and 15 are not used in this system, the memoryspacedallocated for the Recognition Program in memory 68 is replicatedmany times. The preferred memory space that should be used for theRecognition program is 7800 (Hexadecimal) to 7FFF (Hexadecimal).

The Picture Buffer is first located in memory at 1000 (Hexadecimal) to1007(Hexadecimal).

The Asynchronous Communications Interface Adaptor (ACIA) 66, conforms toanElectronic Industries Association Standard RS232C having a port firstlocated in memory at 1400 (Hexadecimal) to 17FF (Hexadecimal).

The output terminals at customer Input/Output port 40 provide a wiredcommunication path which consists of Receive Data and Transmit Data.This path provides means for connection to the Host Processor (notshown).

The reader is also provided with two control sensors 70, 71 that arephysically mounted on wall 23 at opposite sides of the viewing slot 53(FIG. 5). They enable the recognition processor 65 to identify thedirection of travel of each document 10 moved through the slot 22. Theyare operably connected to the sensor port shown at 72.

Various modifications might be made with respect to specific electroniccomponents of this invention. The functional attributes of thesecomponents are therefore the only details believed to be essential to anunderstanding of the invention disclosure.

Having described our invention, we claim:
 1. In an apparatus for readinga longitudinal strip of visual indicia containing discrete alpha-numericcharacters located along the face of a document, wherein the documenthas a constant thickness and its face is bounded along one side by aplanar longitudinal reference edge, the document having a predeterminedwidth dimension perpendicular to the reference edge, the strip of visualindicia being located within transversely spaced boundaries parallel toone another and to the reference edge of the document;a frame; anelongated document slot formed through the length of the frame; saiddocument slot being bounded by a pair of opposed walls on said framehaving opposed inner surfaces spaced apart to freely receive thethickness of a document between them, said walls having coplanarlongitudinal edges and outer ends; said document slot also being boundedby a base on said frame that extends between said pair of walls at alocation spaced inwardly from the longitudinal edges of the walls adistance less than the document height; whereby a document can bemanually moved in a longitudinal direction within the document slot withrespect to the frame, the document being hand-held and guided by slidingengagement of the base by the reference edge of the document; viewingmeans mounted to one of the walls for reflecting light along a scan lineintersecting the path of the strip of visual indicia on a documentwithin the document slot; optical character scanning means on said framefor electronically generating images of each alpha-numeric character asit traverses the scan line; and recognition processing means on saidframe operatively connected to the character scanning means foranalyzing the electronic images generated thereby and for encoding theimages into a machine readable code.
 2. In an apparatus for reading alongitudinal strip of visual indicia containing discrete alpha-numericcharacters located along the face of a document, wherein the documenthas a constant thickness and its face is bounded along one side by aplanar longitudinal reference edge, the document having a predeterminedwidth dimension perpendicular to the reference edge, the strip of visualindicia being located within transversely spaced boundaries parallel toone another and to the reference edge of the document;an enclosurehaving longitudinal outer surfaces bounded by transverse end surfacesand covering a rigid frame; an elongated document slot formed throughthe length of the frame, said document slot being continued through onecorresponding longitudinal outer surface of the enclosure and itstransverse end surfaces; said document slot being bounded within theenclosure by a pair of opposed walls on said frame having opposed innersurfaces spaced apart to freely receive the thickness of a documentbetween them, said walls having coplanar longitudinal edges and outerends; said document slot also being bounded by a base that extendsbetween said pair of walls at a location spaced inwardly from thelongitudinal edges thereof a distance less than the document height;whereby a document can be manually moved in a longitudinal directionwithin the document slot with respect to the frame, the document beinghand-held and guided by sliding engagement of the base by the referenceedge of the document; viewing means mounted to one of the walls forreflecting light along a scan line intersecting the path of the strip ofvisual indicia on a document within the document slot; optical characterscanning means mounted on said frame within the enclosure forelectronically generating images of each alpha-numeric character as ittraverses the scan line; and recognition processing means mounted onsaid frame within the enclosure and operatively connected to thecharacter scanning means for analyzing the electronic images generatedthereby and for encoding the images into a machine readable code.